Interpolation /(?)/

In·ter·po·la·tion

Interpolation

n.
  1. The act of introducing or inserting anything, especially that which is spurious or foreign.
  2. That which is introduced or inserted, especially something foreign or spurious.
    Bentley wrote a letter . . . . upon the scriptural glosses in our present copies of Hesychius, which he considered interpolations from a later hand.
  3. The method or operation of finding from a few given terms of a series, as of numbers or observations, other intermediate terms in conformity with the law of the series. (Math.)